Stabilized halogen-containing resins



Patented Feb. 16, 1954 2,669,548 STABILIZED HALO GEN -CONTAININGL RESINS Joseph. Darby, Richmond Heights, and Leo B.

Jr., St. Louis, Mo., assignors'to Frederiekson,

Monsanto Chemical Com corporation of Delaware pany, St. Louis, Mo a Nix-Drawing. Application January 2,1951, Serial No. 204,092

(CL 260-23) I 16 Claims.

. This invention. relate'sto the stabilization of halogen-containing resin compositions .More particularly this-invention relates to preventing the. deterioration. of halogeni-containingresins at elevated temperatures.

As. iswell known to those skilled in the-art, halogen-.containingresins and particularly halogen-containing. vinylidene resins are subject to deterioration. on exposure to elevated temperatures. Numerous. materials have beensuggested for. incorporationzin. .such .resins to prevent. or minimize such deterioration. However, relatively few of these stabilizing agents have proved to .be particularly efie'ctivei It is an object. of. this. inventionto .provide halogemcontaininggresincompositions having improved resistance to. deterioration on aging. A further object of this invention isto-provide halos gen-containing... vinylidene resin. compositions having increased. resistance .todeterioration .at elevated .-temperatures. A particular object of thisirivention is. tolprovide; vinyl. ch1orideJpoly-.- mer compositions. havingincreasedheat stability.

Accordingto. .the present. invention, halogen.- containing resin. compositions .-having .-improved stability are. attainedby incorporating a halogen-containing resin. atmixture. off a zinc. salt and. a calcium .chelataderivatiye of. a 1,3-:dicarbonyliccompoundcapableiof keto-enol tautomerism.;

The. .following. examples; arexillustrative. .of the inventionbut are: notto be. considered as limitative thereof... Where .parts aremmentioned they are..parts...by. weight.

The compositions in the examples set forthin 'I'ableI. below. are prepared by mixing-100 parts of. polyvinyl. chloride .with. zincstearate andcalcium .ethyl. acetoacetate in. the...amount setforth together with 50 parts of 2-ethyllhexyl. diphenylphosphate. The several ingredientsare mixedon difierential. speed .rolls at a roll temperature of 160*. C. .to' .formhomogeneous. compositions. which are. remoyed. from. the. rolls in. the. form or rough sheets... From these..sheets:...ar.e.- molded finished sheets, which. are about 0.020. inch. in thickness using the. molding. cycle 01 3. minutes: atlfio C.

TABLE I' Zinc h gi l I 0"1 lift M t i y -ace- 0 or or mu es Example toacetate at 160 C. T (Parts) 0.1 3 Slight yellow. 0.2 3 Very sllg'ht yellow. 0. 3 3 I Do. 0.5 3 Do. 0. 9 3 Do. 0.2 5 slight'yellow tinge. 0. 5 1 Very slight yellow.

The unexpected and meritorious nature of applicant's compositions as exemplified by Examples I-VII is clearly evident when it is considered that. on repeating Example II except that the calcium compound is omitted, the product turns. dark brown after only 40 minutes at 160 "C." In further contrast to the compositions of the invention, a product identical with that of Examples I-V'except that the zinc salt is omitted is brown in color after 60 minutes at 160 C.

Results similarto those attained in Examples I-VII are attained .on substituting zinc octate in .the. same amountsfor the zinc stearate in the foregoing examples.

In the same manner as in the examples in Table I, the compositions of the. examples in Table II below are prepared and. tested for heat stability.. In Table-II, the plasticizers employed are designated by the letters A, B, Cand D which stand for, respectively, 2-ethylhexyl diphenyl phosphate, butyl phthalyl'butyl glycolate, dioctyl phthalate and. tricresyl. phosphate.-

Initially, the-sheetsin Examples VIII-EV are substantially colorless.

Asinxthe caseof- Examples I-VII-, each of the compositions. in Examples. VIII-XIV contains parts of polyvinyl chloride in addition to the components set forth in Table II.

As indicated by the stability results, the compositions of Examples VIII-XIV are comparable a in stability to those of Examples I-VII.

In contrast to the stability of the product of Example VIII, when the zinc salt is omitted the result is a product which develops a deep color on heating for 60 minutes at 160 C. In

contrast to the product of Example XI, omission of the calcium compound results in a product which turns black on 20 minutes heating at 160 C. and omission of the zinc salt results in a product which develops a deep color on heating under the same conditions.

The compositions of the examples in Table III below are prepared and treated in the same manner as in the case of the previous examples.

In Example XV the plasticizer is 50 parts of i unsaturated amides, such as acrylic acid amide,

butyl phthalyl butyl glycolate and in Examples XVI-XXI 50 parts of Z-ethylhexyl diphenyl phosphate for each 100 parts of polyvinyl chloride. The amounts of the zinc and calcium salts are also based on 100 parts of polyvinyl chloride.

As in the case of the previous examples, the

products of Examples XV-XXI are substantially colorless prior to the heat stability test as can be seen.

Example XXII A plasticized composition containing 100 parts (iii of a copolymer of 90 parts vinyl chloride and 10 parts vinyl acetate is stabilized by incorporatin therein a mixture of 3 parts calcium ethyl acetoacetate and 0.5 part zinc stearate. The resulting composition possesses improved heat of.

stability characteristics as compared with unstabilized material similar to those of the product of Example IV.

Example XXIII Results similar to those obtained in Example XXII are obtained when the copolymer of vinyl chloride and vinyl acetate therein is replaced by an equal amount of a copolymer of 90 parts vinyl chloride and 10 parts vinylidene chloride.

4 Example XXIV A mixture of 100 parts of a copolymer of 90 parts vinyl chloride and 10 parts diethyl maleate, 50 parts of 2 ethyl hexyl diphenyl phosphate, 3 parts of calcium ethyl acetoacetate and 0.5 part zinc stearate is processed into homogeneous molded sheets as in Example IV. The resulting product exhibits a heat stability comparable to that of the product of Example IV.

As indicated by Examples I-XXEV, it is found that surprisingly efiective stabilizing results are obtained according to the invention with halogen containing resins generally, numerous examples of which are well known to those skilled in the art. Thus, there may be employed resins made from such vinylidene compounds as vinyl chloride, vinylidene chloride, vinyl chloracetate, chloro styrenes, chloro butadienes, etc. Such vinylidene compounds may be polymerized singly or in a mixture with these or other halogencontaining vinylidene compounds or with vinylidene compounds free from halogen. Among the unsaturated materials free from halogen which may be copolymerized with halogen-containing vinylidene compounds are vinyl esters of carboxylic acids, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate; esters of unsaturated acids, for example, alkyl acrylates, such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, allyl acrylate and the corresponding esters of methacrylic acid; vinyl aromatic compounds, for example, styrene, paraethyl styrene, divinyl benzene, vinyl naphthalene, alpha-methyl styrene; dienes, such as butadiene,

acrylic acid anilide; unsaturated nitriles, such as acrylic acid nitrile; esters of a s-unsaturated carboxylic acids, for example, the methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, allyl, methallyl, and phenyl esters of maleic, crotonic, itaconic, fumaric acids and the like. The class of copolymers in which a predominant portion, i. e., more than 50% by weight, of the copolymer is made from a halogen-containing vinylidene compound such as vinyl chloride represents a preferred class of polymers to be treated according to the invention.

Among the preferred embodiments of the invention is the stabilization of polymers prepared t by the copolymerization of vinyl halides, e. g.,

vinyl chloride with lip-unsaturated polycarboxylic acids such as diethyl maleate or other esters of maleic, fumaric, aconitic, itaconic acids, etc. Among'the preferred esters of such acids are alkyl esters in which the alkyl group contains not over eight carbon atoms.

The stabilizer of the invention is also effective when intimately mixed with halogen-containing resins in which part or all of the halogen is introduced into preformed resin, e. g., chlorinated polyvinyl acetate, chlorinated polystyrene. chlorinated polyvinyl chloride, chlorinated natural and synthetic rubbers, rubber hydrochloride, etc.

The stabilizer mixture of the invention is also effective in halogen-containing resins containing halogens other than chlorine, e. g., bromine. fluorine and iodine.

The halogen-containing resins may contain a varying proportion of halogen depending upon the nature of the resin and its contemplated use.

However, as indicated above, vinyl chloride poly-' mers in which the proportion of vinyl chlorideunits amounts to 50% or more of the total mono-' mer used in making'the polymeric product representsz-arpreferred.jclasstcit polymerase-t s i bilized. according: to. the; invention. :1

The amounts of the components of'the sta'e bilizer. combinationiof.thisainvention; may be substantiallyvaried and still resultin surprising improvement in stability of the;.ha1ogen. con: taining resin. Usuallyat least one partby-weight of. the calcium compound. is, used in stabilizing l0llrpar=ts by weight of.ahalogemcontaining resin and generally from 2 to. -parts .byweight are-preferred. The 1186:0f' less-than one partby weight a is efiective to. a considerable :degree. and amounts larger than :10. partsmay-be used al.- though. further improvement in stability of the resulting. compositions. --is not indirect proportion to the amount used.

Usually theamount. of theazinc. salt; is smaller than that. of. the calcium.-compound. Extremely small. amountsfof the .zinc. salt have a.-noticeable effect-on the. stability but, usually at least- 0;05. part by. Weight for every'lOd parts by weight of halogen containing resin is employed and. preferably from 0.1 part to: 0.5part. Amountslarger than; 0.5 part may lie -employed but generally speaking, it is more than =1-2' parts ofi-th'e zinc salt.

Various zinc salts. may be. employed in: the stabilizer combination of the invention, fors'exe ample, zinctsaltsoforganic acids;.as'well.as zinc salts of inorganic acids-xwhichrgive' a. neutral. or

alkaline reaction in an aqueous .medium, i..e., zinc saltsof weak-inorganic acids: Examples of zinc saltssof. organic. acids which may: be" employed are those made from suchraeids as satu'-.

rated aliphatic acids, e. g., ethanoic, propanoic, butanoic, pentanoiahexanoic'; hepanoic, octanoic, nonanoiadecan'oic, hendecanoic'. dodecanoic, tetradecanoic, hexadecanoic and octa-decanoic; monoriolefinici-unsaturated aliphaticacids' such as propenoic acid, .Z-butenoic acid, z' methyl-2-propenoic acid, 3-butenoic acid, 2-pentenoic acid, 4- pentenoic acid, Z-methyl-Z-butenoic acid, 2-hexenoic acid, 7-hexade'cenoic acid,- IO-undetenoic acid, 13-d'ocosenoic acid, 3-hexenoic acid,1and 9'- octadecenoic acid; diolefinic-unsaturated aliphatic acids such as 2,4 pentadienoic acid, 2,4- hexadienoic acid, 3,7-dimethyl-2,6-0ctadien0ic acid, 9,12-octadecadienoic acid; ,triolefinic-unsaturated aliphatic acids such as 3,7-dimethyl- 2,4,6-0ctatrienoic acid, 9,12,15-octadecatrienoic acid, 9,11,13-octadecatrienoic acid; substituted olefinic acids, for example, such hydroxy olefinic acids as 2-hydroxy-3-butenoic acid, 16-hydroxy- 7-hexadecenoic acid and 12-hydroxy-9-octadecenoic acid; acetylenic unsaturated aliphatic acids such as propynoic, butynoic, pentynoic, amyl propynoic, 7-hexadecynoic, 9-octadecynoic and l3-docosynoic acids.

Mixtures of aliphatic acids may be employed, as for example, mixtures of acids occurring in various oils, as for example, linseed, castor, tung, soya bean, perilla, corn, cotton seed, sunflower, safilower, sesame, poppy seed, walnut, peanut, olive, rape seed, whale, dehydrated castor, palm kernel, cocoanut oil and the like.

Other zinc salts of organic acids may also be used such as zinc salts of aliphatic polycarboxylic acids, e. g., zinc salts of maleic, succinic, adipic and sebacic acids, etc., as well as polycarboxylic acids obtained by polymerization of unsaturated fatty acids, e. g., oleic acid dimer and linoleic acid dimer; salts of aromatic acids, e. g., zinc salts of phenyl-acetic, benzoic, phthalic and salicylic acids; salts of cyclic acids, e. g., the zinc salt of abietic acid.

not advantageous to -incorporate phate, 2-ethylhexyl -Iheazincisaitsnn wbef-eithespdurakbehest? saltsiwhen-monocarboxylicsacidsrareusedl: Mixed salts made from mixtures of acids may alsdibe used.

As examplescof; zinc-. .salts.;o.wealezinoli anim acidsgarezinc;saltsotcarbonic..siliciazboricacids and the like.

of: the yariou t'zinc. salts. which .maxab iused in; the stabilizer: combin.ation. of, the-a; inventiomi a preferred class comprises those made from sets urated' monocarboxylic; aliphatici acids containing at least-.110. carbon-atoms; .e as 1.0.- was. bon atoms such asthose-mentioned-above:

The calcium chelates which: aresusedinrthe stabilizer combination of the invention are. calcium chelates-of derivativesyofi 1,3-dicarbonyl, compounds capable of keto-enol .tautomerisnis such: as beta-diketonesg' beta-ketoacids; and. the estersof betaeketoacidss A.- -preierr.ed classof suchpalcium compounds: are the. calcium chelates. of ethyl acetoacetatea butyl" acetoacetate, 2-ethylbuty1 acetoacetateguze ethylhexyl acetoacetate, N-octyl acetoacetate; phenylacetoacetate, benzyhacetoacetata. pheny1 ethyl, acetoacetate, tolyl; acetoacetate well-as;

other aliphatic and aromatic. esters of; aceto. acetic.- acid. Howeverthe calciumchelate of thefree beta-keto acids such .as;acetoacetic.acid',-. etc:,. may; be. used.- Examples. of. calcium. chelates-inf cliketones. include those. made .from acetyl, ace?- tone, benzyl acetone, diacetyl acetoneaandithez like.

The. stabilizer combination of. the invention-11s.. of particular. importance in.stabilizing-halogens containing resins especially vinyl. chloride 419.18%

mers plasticized. with: phosphate esters. such as the alkyl diary]. phosphatesain which thealkyl' group. contains; 6-14. carbon atoms and 1 the? aryl groups are phenyl' or cresyl.groups, i.,e;-,.,orth0:- metaor paracresykgroups andamixturesthereof" since compositions containing such plasticizers have proved to be. especially. difiicultitoastabilize. Examples of such esters include z-ethylhexyl die phenyl. phosphate, .2-ethylhexyl. dicresyl phos. phenyl cresyl phosphate; hexyl. diphenylphosphate, hexyln'phenyl. cresyl phosphate, hexyl dicresylphosphate. dodecyl diphenyl. phosphate, .dodecylphenyl .cresyL ,phosphate, dodecyl dicresyl'. phosphate,,- ,etci: Mix?" tures of such esters may frequently be used advantageously. The amount of the phosphate ester which is used may be substantially varied depending upon the particular ester and upon the particular use which is contemplated for the plasticized composition. Usually however, from 10 to parts of the esters are used for every 100 parts of vinyl chloride-containing resin.

A particular feature of vinyl chloride polymer compositions of the invention plasticized with certain of the phosphate esters set forth above, is their non-toxicity. Thus, in contrast to prior stabilizers, the stabilizer combination of the invention is non-toxic. Thus, by virtue of the present invention compositions are provided which may be processed, e. g., by calendering into thin films without undue discoloration thereof and the resulting films used in the packaging of food and other uses where toxic efl'ects must be avoided.

As indicated by the examples, plasticizers other than alkyl diaryl phosphate esters may be employed as well as mixtures of such phosphate esters and such conventional plasticizers as dioctyl phthalate, tricresyl phosphate, butyl phthalyl butyl *glycolate, etc. In the'case of certain halogen-containing resins no plasticizers are required.

In addition to the stabilizer combination of the invention, other heat stabilizers and also light stabilizers may be included, if desired, examples of which are well known to those skilled in the art as well as other conventional additives such as other resins, lubricants, coloring materials, etc.

The foregoing description is given in illustration and not in limitation of the invention as set forth in the appended claims.

What is claimed is:

l. A composition resistant to the discoloring effects of heat comprising 100 parts by weight of a ha1oge11-ccntaining resin and as a stabilizer therefor a mixture of 0.05 to 2 parts by weight of a zinc salt from the group consisting of zinc salts of organic acids and zinc salts of inorganic acids which give a non-acidic reaction in an aqueous medium and 1 to 10 parts by weight of a calcium chelate derivative of a 1,3-dicarbonylic compound capable of keto-enol tautomerism, the quantity of said zinc salt being smaller than the quantity of the said calcium chelate.

2. A composition as defined in claim 1 in which the halogen is chlorine.

3. A composition as defined in claim 1 in which the calcium chelate derivative is calcium ethyl acetoacetate.

4. A composition resistant to the discoloring efiects of heat comprising 100 parts by weight of a halogen-containing vinylidene resin and as a stabilizer therefor a mixture of 0.1 to 0.5 parts by weight of a zinc salt of an organic acid and 2 to 10 parts by Weight of a calcium chelate derivative of a 1,3-dicarbonylic compound capable of keto-enol tautomerism.

5. A composition as defined in claim 4 in which the halogen is chloride.

' 6. A composition as defined in claim 4 in which the zinc salt is a zinc salt of a monocarboxylic saturated aliphatic acid containing at least 10 carbon atoms.

7. A composition as defined in claim 4 in which the resin is a vinyl chloride polymer.

8. A composition as defined in claim 4 in which the resin is polyvinyl chloride.

8 "9. A composition as defined in claim 4 in which the resin is a vinyl chloride-vinyl acetate copolymer.

10. A composition as defined in claim 4 in which the resin is a vinyl chloride-diethyl maleate copolymer.

' 11. A heat resistant composition comprising 100 parts by weight of a vinyl halide polymer and as a stabilizer therefor a mixture of 0.1 to 0.5 parts by weight of zinc stearate and 2 to 10 parts by weight of calcium ethyl acetoacetate.

12. A heat resistant composition comprising 100 parts by weight of a vinyl chloride polymer and as a stabilizer therefor a mixture of 0.1 to 0.5 parts by weight of zinc stearate and 2 to 10 parts by weight of calcium ethyl acetoacetate.

13. A heat resistant composition comprising 100 parts by weight of polyvinyl chloride, a phosphate ester plasticizer and as a stabilizer therefor a mixture of 0.1 to 0.5 parts by weight of zinc stearate and 2 to 10 parts by weight of calcium ethyl acetoacetate.

14. A composition as defined in claim 13 in which the phosphate plasticizer is an alkyl diaryl phosphate in which the alkyl group contains from 6 to 14 carbon atoms and the aryl radical is taken from the group consisting of phenyl and cresyl radicals.

15. A composition as defined in claim 12 in which the polymer is a vinyl chloride-vinyl acetate copolymer.

16. A composition as defined in claim 12 'in which the polymer is a vinyl chloride-diethyl maleate copolymer.

JOSEPH R. DARBY. LEO D. FREDERICKSON, J R.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A COMPOSITION RESISTANT TO THE DISCOLORING EFFECTS OF HEAT COMPRISING 100 PARTS BY WEIGHT OF A HALOGEN-CONTAINING RESIN AND AS A STABILIZER THEREFOR A MIXTURE OF 0.05 TO 2 PARTS BY WEIGHT OF A ZINC SALT FROM THE GROUP CONSISTING OF ZINC SALTS OF ORGANIC ACIDS AND ZINC SALTS OF INORGANIC ACIDS WHICH GIVE A NON-ACIDIC REACTION IN AN AQUEOUS MEDIUM AND 1 TO 10 PARTS BY WEIGHT OF A CALCIUM CHELATE DERIVATIVE OF A 1,3-DICARBONYLIC COMPOUND CAPABLE OF KETO-ENOL TAUTOMERISM, THE QUANTITY OF SAID ZINC SALT BEING SMALLER THAN THE QUANTITY OF THE SAID CALCIUM CHELATE. 